A static charge can quickly build up in a piece of acrylic.
This has been a traditional problem in sign shops when painting plastic faces for lighted signs.
When spray painting acrylic second surface it is always important to thoroughly neutralize static just before spraying, otherwise, the spray job will not be even, but mottled and splotchy. Traditionally, static is removed with a chamois wipe of alcohol and water (a chamois leather removes static better than a rag). This is best done a few minutes just before spraying. Sometimes, when spraying several colors, it's even necessary to do a static wipe in between each color. It was always my practice to wipe both sides of acrylic, front and back, at the beginning of every painting session.
If a static wipe is done too far in advance of painting, it can build back up before you start spraying. At one shop that had a particularly bad problem with static, I kept a dish soap bottle full of water in the paint booth within easy reach. When the static seemed to be building up, I would stop spraying paint and squirt water onto the back of the plastic and then continue spraying while the water was running down the back.
When hand lettering, acrylic can have enough of a static charge to pull the paint right out of the tip of the lettering brush from as far away as a half inch. It looks like tiny, spidery strings flowing from the hairs through the air.
Since static can cause so much trouble when painting, it's no surprise that it can interfere with the ink while digitally printing as well.
And if you ever apply clear prints to acrylic second surface, and you can't seem to do it without getting some dust particles trapped under the print no matter how much you cleaned the surface, try gently wiping the acrylic with a damp chamois instead of a paper towel or tack cloth. It removes dust and neutralizes static at the same time. A tack cloth can sometimes even re-introduce static.
My test for static is to hold the back of my hand close to the surface of the plastic. Static is still present if I can feel electricity tug at the hair on the back of my hand.
